Hill Country State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hill Country State Natural Area clear sky chart from 2005-11-06 to 2024-09-14.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	14% 6% 2 5% 4 4 4 3 5% 7% 47%	100401
	Night	14% 5% 2 4 3 3 3 3 4 7% 52%	97589
Transparency	Day	36% 6% 10% 21% 18% 9%	100212
	Night	33% 5% 11% 20% 18% 12%	97449
Seeing	Day	15% 8% 23% 30% 21% 4	14598
	Night	16% 7% 24% 37% 15% 1	24505

By Month

Percentage Cloud Cover SE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	14% 7% 2 3 2 2 2 2 3 6% 56%	2847
	11th to 20th	Day	16% 5% 2 3 2 2 2 3 4 4 57%	2896
	21st to end	Day	18% 8% 2 4 3 3 3 3 5% 9% 44%	3487
February	1st to 10th	Day	17% 7% 2 6% 4 3 3 2 4 4 47%	1900
	11th to 20th	Day	20% 7% 2 5% 3 2 3 3 5% 5% 45%	1849
	21st to end	Day	18% 5% 2 4 2 2 3 2 4 6% 51%	1570
March	1st to 10th	Day	18% 9% 2 5% 3 3 3 3 3 5% 46%	3298
	11th to 20th	Day	24% 9% 3 8% 4 4 4 3 4 4 34%	3480
	21st to end	Day	18% 5% 2 4 2 3 3 3 4 7% 47%	3814
April	1st to 10th	Day	16% 7% 2 6% 4 3 4 3 5% 6% 45%	2090
	11th to 20th	Day	20% 5% 2 5% 3 4 4 4 5% 6% 44%	2173
	21st to end	Day	18% 7% 2 5% 4 4 4 3 4 5% 44%	2332
May	1st to 10th	Day	25% 7% 2 6% 4 4 4 3 4 6% 34%	4082
	11th to 20th	Day	16% 5% 2 5% 4 4 4 3 5% 7% 44%	4082
	21st to end	Day	14% 6% 2 6% 5% 5% 5% 4 6% 9% 39%	4477
June	1st to 10th	Day	8% 5% 2 5% 4 4 5% 4 6% 9% 47%	2470
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 6% 9% 45%	2470
	21st to end	Day	10% 6% 2 6% 6% 6% 6% 5% 6% 8% 39%	2470
July	1st to 10th	Day	9% 5% 2 5% 5% 5% 5% 4 5% 8% 47%	4120
	11th to 20th	Day	6% 4 2 6% 5% 5% 5% 4 7% 9% 48%	4120
	21st to end	Day	8% 6% 2 6% 4 5% 6% 5% 7% 10% 40%	4465
August	1st to 10th	Day	2 2 1 3 3 3 3 4 5% 9% 68%	3828
	11th to 20th	Day	4 3 1 4 3 4 4 3 6% 10% 59%	3726
	21st to end	Day	5% 4 1 5% 5% 5% 5% 4 6% 10% 49%	4101
September	1st to 10th	Day	12% 6% 3 7% 5% 6% 5% 4 6% 7% 40%	2090
	11th to 20th	Day	11% 7% 2 6% 5% 5% 5% 5% 6% 6% 42%	2013
	21st to end	Day	10% 5% 3 6% 5% 4 5% 4 6% 7% 46%	1980
October	1st to 10th	Day	8% 5% 2 5% 4 5% 4 3 5% 8% 52%	1980
	11th to 20th	Day	16% 4 2 4 3 3 4 3 4 5% 51%	1936
	21st to end	Day	14% 4 2 5% 3 3 2 2 3 4 57%	1980
November	1st to 10th	Day	19% 8% 2 5% 3 3 3 2 5% 6% 45%	1849
	11th to 20th	Day	15% 7% 2 5% 3 3 4 3 5% 5% 48%	1710
	21st to end	Day	19% 6% 3 5% 3 2 4 3 3 4 47%	1710
December	1st to 10th	Day	16% 8% 2 5% 3 3 3 2 4 6% 47%	1710
	11th to 20th	Day	18% 8% 1 5% 3 4 4 2 4 5% 46%	2161
	21st to end	Day	17% 5% 2 3 3 2 2 3 3 4 56%	3135
January	1st to 10th	Night	17% 4 1 4 2 2 3 2 4 6% 55%	4108
	11th to 20th	Night	12% 5% 1 3 2 2 1 2 2 4 66%	4088
	21st to end	Night	21% 6% 2 6% 3 2 2 2 4 5% 46%	4180
February	1st to 10th	Night	17% 6% 1 4 3 2 2 2 4 6% 52%	2280
	11th to 20th	Night	19% 6% 1 5% 3 2 2 2 4 4 51%	2218
	21st to end	Night	17% 6% 2 5% 3 3 4 2 4 7% 48%	1884
March	1st to 10th	Night	18% 8% 2 5% 3 3 3 3 4 5% 44%	3557
	11th to 20th	Night	22% 10% 3 7% 4 3 3 2 4 4 37%	3480
	21st to end	Night	18% 6% 2 4 3 3 4 3 4 5% 48%	3817
April	1st to 10th	Night	15% 6% 1 4 4 3 3 4 4 6% 49%	2090
	11th to 20th	Night	21% 6% 2 5% 3 2 3 3 3 5% 47%	1951
	21st to end	Night	21% 5% 2 4 3 3 3 3 3 5% 48%	1846
May	1st to 10th	Night	27% 7% 2 4 3 3 3 2 4 6% 39%	2823
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 4 6% 51%	2823
	21st to end	Night	16% 6% 2 4 4 3 4 2 5% 8% 47%	3090
June	1st to 10th	Night	6% 3 1 2 3 3 4 4 6% 9% 59%	1710
	11th to 20th	Night	7% 3 2 4 4 3 4 4 5% 8% 58%	1710
	21st to end	Night	9% 5% 1 4 3 4 3 4 5% 11% 52%	1710
July	1st to 10th	Night	6% 4 1 4 4 4 4 3 6% 10% 52%	2850
	11th to 20th	Night	5% 4 1 5% 4 4 4 4 7% 10% 52%	2850
	21st to end	Night	12% 7% 2 6% 3 4 4 4 6% 9% 43%	3098
August	1st to 10th	Night	2 2 1 3 2 2 2 2 4 7% 71%	3107
	11th to 20th	Night	4 2 1 3 3 3 4 3 6% 9% 61%	3113
	21st to end	Night	6% 5% 1 4 3 4 4 3 6% 10% 54%	3549
September	1st to 10th	Night	10% 6% 2 6% 4 5% 4 3 5% 8% 47%	2090
	11th to 20th	Night	11% 7% 2 6% 3 4 4 3 7% 8% 45%	2024
	21st to end	Night	9% 5% 2 6% 3 4 4 3 5% 7% 51%	1980
October	1st to 10th	Night	8% 4 1 5% 3 3 3 3 5% 5% 60%	1980
	11th to 20th	Night	15% 4 1 4 3 3 3 3 5% 6% 53%	2004
	21st to end	Night	16% 4 2 3 2 2 2 1 3 4 62%	2376
November	1st to 10th	Night	15% 6% 2 4 3 3 2 2 4 6% 53%	2225
	11th to 20th	Night	12% 5% 2 4 3 3 3 2 5% 6% 55%	2470
	21st to end	Night	20% 5% 1 4 3 3 3 3 5% 7% 48%	2470
December	1st to 10th	Night	16% 5% 2 3 3 3 3 2 4 6% 53%	2470
	11th to 20th	Night	18% 7% 2 5% 3 3 3 2 3 5% 48%	3036
	21st to end	Night	20% 5% 2 3 2 2 2 2 3 6% 53%	4532

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	30% 5% 4 15% 26% 20%	2848
	11th to 20th	Day	32% 2 5% 14% 27% 19%	2896
	21st to end	Day	39% 4 6% 14% 28% 10%	3487
February	1st to 10th	Day	41% 3 5% 12% 21% 17%	1900
	11th to 20th	Day	42% 4 6% 16% 19% 14%	1859
	21st to end	Day	37% 3 7% 17% 19% 17%	1570
March	1st to 10th	Day	42% 4 6% 13% 22% 13%	3298
	11th to 20th	Day	54% 5% 5% 10% 16% 10%	3480
	21st to end	Day	36% 6% 10% 16% 18% 15%	3814
April	1st to 10th	Day	40% 4 8% 15% 18% 14%	2090
	11th to 20th	Day	41% 6% 6% 17% 17% 13%	2173
	21st to end	Day	42% 4 7% 18% 17% 12%	2332
May	1st to 10th	Day	49% 7% 9% 15% 13% 7%	4120
	11th to 20th	Day	38% 7% 10% 19% 19% 8%	4086
	21st to end	Day	38% 9% 12% 27% 11% 2	4489
June	1st to 10th	Day	30% 8% 14% 25% 19% 3	2470
	11th to 20th	Day	35% 6% 12% 25% 17% 6%	2470
	21st to end	Day	40% 8% 11% 24% 14% 4	2470
July	1st to 10th	Day	32% 7% 16% 37% 7% 1	4056
	11th to 20th	Day	29% 7% 18% 28% 16% 1	4051
	21st to end	Day	34% 8% 19% 28% 11% 1	4325
August	1st to 10th	Day	14% 5% 11% 43% 25% 1	3814
	11th to 20th	Day	20% 7% 22% 38% 12% 2	3762
	21st to end	Day	29% 9% 18% 24% 19% 2	4100
September	1st to 10th	Day	42% 7% 10% 17% 16% 7%	2090
	11th to 20th	Day	39% 8% 11% 19% 17% 6%	2013
	21st to end	Day	35% 6% 10% 22% 18% 9%	1980
October	1st to 10th	Day	31% 6% 10% 21% 25% 8%	1980
	11th to 20th	Day	35% 5% 8% 17% 19% 16%	1936
	21st to end	Day	32% 4 5% 16% 24% 20%	1980
November	1st to 10th	Day	41% 4 8% 20% 17% 11%	1849
	11th to 20th	Day	39% 4 6% 17% 19% 16%	1710
	21st to end	Day	42% 3 5% 15% 20% 14%	1710
December	1st to 10th	Day	39% 4 8% 18% 21% 10%	1710
	11th to 20th	Day	41% 4 6% 10% 21% 16%	2159
	21st to end	Day	33% 3 5% 16% 29% 15%	3135
January	1st to 10th	Night	30% 5% 5% 14% 23% 23%	4108
	11th to 20th	Night	25% 2 4 17% 27% 25%	4088
	21st to end	Night	41% 4 4 12% 26% 13%	4180
February	1st to 10th	Night	35% 4 7% 13% 21% 20%	2280
	11th to 20th	Night	38% 3 5% 16% 21% 17%	2218
	21st to end	Night	38% 4 6% 16% 19% 17%	1884
March	1st to 10th	Night	41% 5% 7% 15% 20% 12%	3557
	11th to 20th	Night	48% 7% 7% 12% 13% 12%	3480
	21st to end	Night	37% 6% 10% 15% 18% 14%	3817
April	1st to 10th	Night	34% 5% 11% 17% 17% 16%	2090
	11th to 20th	Night	40% 4 9% 13% 17% 17%	1951
	21st to end	Night	41% 4 9% 19% 16% 12%	1846
May	1st to 10th	Night	44% 7% 10% 17% 12% 10%	2850
	11th to 20th	Night	33% 7% 10% 22% 19% 8%	2824
	21st to end	Night	36% 7% 13% 28% 12% 4	3099
June	1st to 10th	Night	21% 6% 19% 31% 20% 3	1710
	11th to 20th	Night	24% 6% 15% 28% 21% 5%	1710
	21st to end	Night	29% 7% 18% 28% 15% 3	1710
July	1st to 10th	Night	25% 7% 24% 37% 5% 1	2805
	11th to 20th	Night	25% 9% 21% 28% 16% 2	2796
	21st to end	Night	35% 8% 22% 26% 8% 1	2999
August	1st to 10th	Night	13% 5% 16% 44% 21%	3097
	11th to 20th	Night	19% 7% 29% 36% 8% 1	3143
	21st to end	Night	25% 11% 21% 25% 17% 2	3549
September	1st to 10th	Night	35% 6% 14% 21% 16% 7%	2090
	11th to 20th	Night	35% 8% 16% 21% 15% 6%	2024
	21st to end	Night	31% 6% 13% 22% 18% 10%	1980
October	1st to 10th	Night	26% 4 12% 26% 21% 11%	1980
	11th to 20th	Night	32% 4 10% 17% 20% 16%	2004
	21st to end	Night	29% 3 6% 15% 25% 22%	2376
November	1st to 10th	Night	33% 4 7% 19% 22% 14%	2225
	11th to 20th	Night	31% 4 9% 19% 20% 16%	2470
	21st to end	Night	37% 4 8% 16% 19% 15%	2470
December	1st to 10th	Night	34% 4 8% 19% 22% 13%	2470
	11th to 20th	Night	40% 4 5% 14% 17% 20%	3037
	21st to end	Night	34% 4 5% 14% 27% 16%	4532

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	22% 13% 33% 25% 7%	270
	11th to 20th	Day	25% 15% 26% 25% 9%	270
	21st to end	Day	19% 15% 33% 23% 8%	297
February	1st to 10th	Day	30% 13% 26% 23% 9%	270
	11th to 20th	Day	27% 19% 31% 16% 6%	270
	21st to end	Day	24% 19% 36% 17% 4	225
March	1st to 10th	Day	26% 14% 40% 17% 3	270
	11th to 20th	Day	19% 19% 41% 17% 4	270
	21st to end	Day	22% 18% 42% 16% 2	297
April	1st to 10th	Day	23% 17% 34% 23% 3	270
	11th to 20th	Day	18% 17% 38% 24% 4	371
	21st to end	Day	19% 13% 42% 22% 3	512
May	1st to 10th	Day	21% 10% 36% 27% 6%	653
	11th to 20th	Day	19% 8% 32% 31% 8% 2	675
	21st to end	Day	19% 6% 31% 32% 11% 1	734
June	1st to 10th	Day	8% 2 21% 43% 24% 3	680
	11th to 20th	Day	10% 2 19% 45% 22% 2	680
	21st to end	Day	10% 1 16% 39% 28% 6%	680
July	1st to 10th	Day	12% 2 11% 34% 33% 7%	671
	11th to 20th	Day	7% 1 6% 35% 44% 6%	668
	21st to end	Day	5% 2 8% 33% 42% 10%	739
August	1st to 10th	Day	3 3 37% 44% 13%	517
	11th to 20th	Day	5% 1 6% 37% 40% 11%	477
	21st to end	Day	6% 1 7% 30% 41% 15%	499
September	1st to 10th	Day	11% 2 9% 27% 36% 14%	300
	11th to 20th	Day	9% 3 29% 44% 15%	279
	21st to end	Day	7% 1 11% 27% 43% 10%	270
October	1st to 10th	Day	8% 2 16% 35% 33% 6%	270
	11th to 20th	Day	13% 4 22% 38% 19% 4	270
	21st to end	Day	18% 15% 25% 26% 15% 1	297
November	1st to 10th	Day	21% 6% 28% 25% 16% 3	270
	11th to 20th	Day	24% 10% 24% 27% 12% 3	270
	21st to end	Day	25% 16% 32% 17% 9% 1	270
December	1st to 10th	Day	17% 13% 27% 28% 12% 3	270
	11th to 20th	Day	24% 15% 28% 24% 9%	270
	21st to end	Day	23% 11% 33% 25% 8%	297
January	1st to 10th	Night	19% 8% 26% 37% 10%	950
	11th to 20th	Night	21% 9% 29% 34% 8%	931
	21st to end	Night	23% 9% 26% 34% 8%	836
February	1st to 10th	Night	23% 12% 27% 30% 8%	760
	11th to 20th	Night	26% 10% 30% 28% 6%	744
	21st to end	Night	22% 11% 38% 28% 2	628
March	1st to 10th	Night	23% 11% 33% 28% 4 1	661
	11th to 20th	Night	20% 12% 33% 31% 4	570
	21st to end	Night	19% 12% 38% 26% 5%	627
April	1st to 10th	Night	14% 11% 41% 31% 3	570
	11th to 20th	Night	21% 10% 43% 24% 2	563
	21st to end	Night	21% 11% 40% 23% 5%	570
May	1st to 10th	Night	17% 10% 41% 27% 5%	570
	11th to 20th	Night	17% 7% 36% 33% 7% 1	561
	21st to end	Night	17% 7% 32% 35% 8%	617
June	1st to 10th	Night	6% 2 26% 46% 18% 1	570
	11th to 20th	Night	7% 2 32% 46% 14%	570
	21st to end	Night	8% 3 20% 46% 22% 1	570
July	1st to 10th	Night	9% 3 12% 47% 28% 1	555
	11th to 20th	Night	4 1 13% 52% 30% 1	552
	21st to end	Night	7% 2 9% 50% 31% 2	624
August	1st to 10th	Night	2 1 9% 48% 38% 2	567
	11th to 20th	Night	5% 8% 52% 32% 3	564
	21st to end	Night	6% 2 8% 39% 41% 4	627
September	1st to 10th	Night	11% 1 9% 42% 32% 5%	570
	11th to 20th	Night	12% 1 9% 42% 34% 2	552
	21st to end	Night	11% 2 12% 41% 30% 4	540
October	1st to 10th	Night	8% 2 13% 49% 26% 2	540
	11th to 20th	Night	16% 3 21% 40% 17% 3	564
	21st to end	Night	16% 7% 22% 30% 23% 2	792
November	1st to 10th	Night	14% 6% 19% 37% 21% 2	745
	11th to 20th	Night	15% 7% 19% 42% 16% 2	950
	21st to end	Night	22% 9% 23% 33% 13% 1	950
December	1st to 10th	Night	19% 7% 22% 38% 13% 1	950
	11th to 20th	Night	24% 10% 24% 32% 10%	950
	21st to end	Night	20% 8% 26% 37% 9% 1	1045

Page generated at 2024-09-11 09:00:03. Version ac07

Copyright © 2024 Attilla Danko.